Every day, staff at Sunrise Radio were greeted with a smile from Geeta Aulakh, the receptionist who had dreamed as a young girl of working for the first independent 24-hour Asian station.

For four days this week, her chair has been empty and, in a painful series of conversations, her colleagues have been sharing glimpses she gave them of the pain hidden beneath her warmth.

It is in the particularly horrific death of Aulakh that the secrets of her life are emerging. Police believe what spilled out on to the street in Greenford, west London, on Monday evening was the violent culmination of something hidden in Aulakh's recent past.

Senior sources believe the 28-year-old was held down by more than one assailant and struck repeatedly with either a sabre or a machete as she went to pick up her two sons from their childminder. Aulakh was just 100 metres away from her young children, on a quiet street lined with unremarkable postwar terraced houses, where residents fear burglary or car crime, not the sort of scene they experienced that night.

The Guardian understands that detectives have been given a detailed account of the attack by a handful of key witnesses.

In the frenzied assault, Aulakh was struck repeatedly around the head with the sabre-like weapon. She fought for her life, sustaining a serious wound to her right hand which severed it from her arm, leading to speculation that it was cut off deliberately in some sort of religious ritual. The suggestion is a distraction, sources say. The wound was a classic defence injury against an assault with a long, extremely sharp weapon.

The choice of location was deliberate, police believe. They say it was no random attack, but a planned assault by more than one assailant on a woman whose regular routine was known.

The nearness to her children is, again, no coincidence. "We are not talking about a stranger attacker here who she does not know. It is complicated but what you are looking at is a fairly closed group of people," said police.

Around the corner from where Aulakh was trying to fight off her assailants, her childminder, Safeen Arif, heard nothing but was growing worried.

"She was so devoted to her boys, she would do anything for them," said Arif. "She would always call me if she was going to be late. That's why I started ringing her on Monday when she didn't arrive, but no one answered her phone."

Like colleagues at Sunrise Radio, Arif knew Aulakh as a happy, warm person who had separated from her husband and was seeking a divorce, but was getting on with her life, trying to do the best for her children.

It is only now as people talk about her murder that some friends are sharing conversations in which Aulakh suggested she was frightened and felt harassed but did not specify who was causing her sense of feeling terrorised.

Dr Avtar Lit, her boss at the radio station, said: "She was a very private person. What is emerging now is that Geeta did share with some of her female colleagues that she felt frightened and harassed, but she didn't reveal a great deal, and little bits of what she said are coming out now."

Born Geeta Shinh, she grew up in Southall, west London in a middle-class family with two brothers and two sisters. When she was 17, she met husband-to-be Harpreet, known as Sunny, and the couple fell in love.

However, her mother, who worked in a GP's surgery, and her father, a warehouseman, were unhappy about the match as Harpreet was unemployed and seemed to have no prospects.

It is unclear if there was a rift with her family, but friends say the young couple decided to put some space between them and relatives, leaving the UK to spend some time in Belgium.

Despite her parents' early misgivings, the marriage produced two boys, now 10 and eight. Three years ago this week, when she was back in London, Aulakh obtained the Sunrise Radio job in Southall. "She was a very important part of the office, always smiling, always helpful," said Lit. "She once told me that she'd grown up listening to Sunrise and it was her dream to work there when she was an adult."

But there were some signs of something amiss within her personal life. During one argument at home in September 2002, she had been concerned enough to dial 999 late at night. When officers arrived, she refused to file a complaint and the incident was marked as "no crime".

The same happened last October; officers arrived at her home but no complaint was filed and "no crime" was recorded.

By last October, Aulakh had separated from her husband and is understood to have been living in a council house in Greenford.

Myrah Mistry, who knew her for 17 years, said: "She wasn't happy, so she left. He was trying to get back with her but she didn't want to. I think she was thinking about divorce – she was going down that road. He used to call her quite often, he would sometimes come into the radio station."

On Monday night, Aulakh left work at 6.15pm with two female friends. She walked to Southall railway station where her friends boarded their trains and she got on to her bus, which made its way north to Greenford, where she was due to pick up her children from her childminder in Braund Avenue. Only two days, before she had celebrated her youngest son's eighth birthday.

Police are studying CCTV footage from Southall station and the bus to see when she might have been followed by her killers. But, so far, the trail of images stops once she gets off the bus and heads towards the childminders.

At about 7pm, her death and its brutality was marked by nothing more than the kind of sound often heard on a London street and quickly dismissed – a single scream overheard by a schoolgirl as she sat in her bedroom doing her homework.

Three and a half hours later, Aulakh's mother, Nardesh, arrived at her bedside in Charing Cross hospital. She cried out her daughter's name twice before Aulakh died.

In their investigation into the murder, detectives are probing every aspect of Aulakh's past, attempting to unpick the secrets she guarded so closely. They say they have ruled out a so-called honour killing as a motive but admit that the circle they are investigating is one close to Aulakh herself.

For many who work in the field of violence against women and "honour" crime within the Asian community, the revelations emerging about Geeta's life are all too familiar.

Sudharshan Bhuhi, who runs a 24-hour helpline for Asian women, said: "It is very early for the police to steer away from 'honour' crime, they should not shy away from using the words," she said. "What is coming out about her is typical of the women we talk to.

"As an Indian woman and a Sikh myself who runs an Asian specific organisation, I know it takes much longer for women from my culture to be able to state these feelings of fear and act on them. All this fear is coming out now, after her death and all we feel here is immense sadness that another human life has been lost unnecessarily."

The 'no crime' controversy

Nowhere is the issue of classifying emergency calls to police as "no crime" more controversial than in domestic disputes. While police have not said domestic violence was a factor in Geeta Aulakh's death, they were called twice to her home and twice marked the incident as "no crime". By their very nature domestic disputes involve a relationship in which one party is vulnerable, afraid of the other and therefore reluctant to stand up publicly and accuse them of assault.

Often the presence of children in a household can result in a woman calling the police to an incident involving a partner and then being reluctant to pursue a complaint for fear of what will happen to her children, retribution by her partner, and financial implications should she have to move out.

A review by Her Majesty's Inspectorate of Constabulary revealed recently that more than a third of cases of violence sampled had been wrongly categorised as not warranting further investigation.

"What they are supposed to do is refer them at least to the community safety unit and they are supposed to refer them to other agencies," said Hannanah Siddiqui, of Southall Black Sisters. "999 calls to potential domestic violence incidents should not be 'no crimed' and simply not investigated."

A review by the Association of Chief Police Officers called for a better bridge between the police and the civil law so that victims can be protected even if they cannot be persuaded to file a complaint against an abusive husband or partner. There also needs to be consideration of a new offence of a "course of conduct" and a determination to pursue perpetrators of domestic violence even when the victim withdraws her complaint, the review said.